Preparations for the external application of antiseptic agents  and/or agents promoting the healing of wounds

ABSTRACT

The present invention relates to liposomal pharmaceutical preparations which include active agents such as antiseptic agents, wound-healing agents, or combinations thereof, useful in the treatment of external wounds. The active agents are encapsulated in liposomes, and the liposomes are incorporated in pharmaceutical preparations such as liquids, ointments, gels, lotions, or creams capable of delivering the active agents to external wound sites. The invention further relates to methods of preparation of the liposomes and the pharmaceutical preparations, and to methods of treatment of external wounds and ophthalmic infections.

BACKGROUND OF THE INVENTION

The invention concerns preparations for the external application ofagents with antiseptic and/or wound healing promoting properties. Thepreparations are specifically applied to wounds, skin, mucous membranesand mucosa-like unkeratinized epithelial tissues of humans and animals.

A plurality of different antibiotic and antiseptic agents are known forthe topical treatment of infectious maladies. A decisive disadvantage ofantibiotic agents is that the infecting bacteria show primaryresistances, and can acquire secondary resistances, against theseagents. Further, antibiotics quite often lead to patient sensitivity,especially after prolonged treatment. The use of antiseptics such aspovidone iodine, also known as polyvidone iodine or PVP iodine, i.e. thepoly(1-vinyl-2-pyrrolidin-2-one)-iodine complex, can inhibit theformation of resistances to antiseptic or antibiotic agents by infectingbacteria. Antiseptic agents are also much more rarely allergenic whenused in patients as compared to antibiotics.

In the scientific literature liposomes have quite often been disclosedas drug carriers. A non-exhaustive list comprises the following, morerecent publications:

Hoekstra, H. J., Van Baare, J., Dutrieux, R. P.: Evaluation of topicaltherapy and wound healing. European Burn Association 5th Congress,Brighton, England, 1993 Neuhann, T., Sommer, G.: Erfahrungen mitJod-Povidon zur Behandlung der Reratokonjunctivitis epidemica. Z. prakt.Augenh. 1 (1980), p. 65;

Pleyer, U., Schmidt, K., Thiel, H. J. (eds.): Liposomes in Ophthalmologyand Dermatology. Hipp krates Verlag Stuttgart, 1993;

Prufer, K., Sternberg, B.: Liposomen in der Medizin-Eine aktuelleBestandsaufnahme. Z. arzt. Fortbildung 88 (1994), pp. 257-256;

Rubas, W., Schreier, H.: Liposomen: Fortschritt inHerstellungs-Technologie und Therapie Pharmazie in unserer Zeit, 6(1991) pp. 255-270;

Schreier, H., Bouwstra, J.: Liposomes as topical drug carriers: dermaland transdermal drug delivery. (Submitted); and

Shell, J. W.: Ophthalmic drug delivery systems. Surv. Opthalmol. 29(1984), 117.

Further, the team of Hoekstra et al. in Beverwijk, Netherlands, hasreported on animal experiments with silver sulfadiazine, achemotherapeutic agent, encapsulated in liposomes and applied toexperimental wounds. The results appear to show agent enrichment at thewound bottom and reduced silver resorption, compared with customarysilver sulfadiazine ointments.

However, although a lot of attention has been paid for quite some timeto liposomes as drug carriers, there appears to be no prior art relatingto liposomes as carriers of antiseptic or wound healing promoting agentsfor external applications.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the instant invention is to provide a well-tolerated,easily applicable antiseptic or wound healing promoting preparation,which provides protracted release and protracted topical effect of theactive agent.

A further object of the present invention is to provide a method ofproducing a pharmaceutically acceptable liposome preparation includingan active agent (e.g. an antiseptic agent or a wound-healing agent).

Another object of the present invention is related to the treatment ofeye infections using a liposomal pharmaceutical preparation containingan antiseptic agent.

It is a further object of the present invention to provide a method oftreating external wounds using a liposomal pharmaceutical formulationwhich formulation includes an antiseptic agent, a wound-healingpromoting agent, or a combination thereof as active ingredients.

According to the invention the technical objects are attained in thatthe preparation comprises at least one antiseptic and/or wound healingpromoting agent in the form of a liposome preparation.

In accordance with the above-stated objectives and others, the presentinvention is directed in part to a pharmaceutical preparation forexternal application which preparation contains an antiseptic agent, awound-healing agent, or a combination thereof, encapsulated in aplurality of liposomes.

An important aspect of the invention is related to the surprising factthat liposomes are highly suited as carriers for antiseptic agents,especially for povidone iodine, and for agents promoting the healing ofwounds.

In certain preferred embodiments, a portion of the antiseptic agent orwound-healing agent or combination thereof is not encapsulated in theliposomes.

In certain preferred embodiments, the antiseptic agent may be selectedfrom mercury compounds, phenol derivatives such as thymol, eugenol andhexachlorophene, detergents, iodine and iodine complexes, or mixtures ofthe foregoing. A particularly preferred embodiment contains povidoneiodine as the antiseptic agent.

The wound-healing agent promotes healing of injured tissue. In certainembodiments of the invention, the wound-healing agent is selected fromthe group consisting of allantoin, an azulene compound, a compound fromthe vitamin B series, or combinations thereof.

A preferred embodiment of the invention contains at least one antisepticagent and at least one wound-healing agent.

Liposome size is also an important aspect of the invention. Preferably,the liposomes in the pharmaceutical preparation are in the range fromabout 20 to about 20,000 nm, more preferably from about 50 to about4,000 nm, even more preferably from about 500 to about 2,50.0 nm, andmost preferably the liposomes are of a uniform diameter of about 1,000nm.

The pharmaceutical preparation according to the invention willpreferably release the antiseptic agent or wound-healing agent orcombination thereof over an extended time period, more preferably overan extended time period of several hours duration (e.g., about 2 toabout 12 hours). A particularly preferred embodiment releases theantiseptic agent or wound-healing agent at the same release rate overthe extended time period.

A preferred pharmaceutical preparation according to the presentinvention preferably includes at least one anesthetically active agent.

The pharmaceutical preparation may also include additional conserving orpreservative agents, and consistency forming additives that arecurrently known to one of ordinary skill in the pharmaceutical art.

The pharmaceutical preparation of the present invention may take avariety of different forms according to the vehicle used. In a preferredembodiment, the vehicle is a liquid and the preparation is in the, formof a solution or a dispersion comprising liposomes. A particularlypreferred embodiment where the pharmaceutical preparation is in the formof a liquid pharmaceutical drop preparation.

In yet another embodiment the vehicle is in the form of a cream base andthe resultant pharmaceutical preparation is in the form of a cream.Other embodiments of the present invention include the pharmaceuticalpreparation in the form of an oil in water or water in oil lotion, anointment, or a gel (preferably a hydrogel base).

Another preferred embodiment of the invention is a pharmaceuticalpreparation in the form of a pharmaceutical eyedrop formulation preparedwith liposomes encapsulating an antiseptic agent (e.g., PVP iodinesolution), and wherein said liposomes are of substantially uniform size.The formulation may additionally comprise customary additives, adjuvantsand auxiliary substances of a pharmaceutical eyedrop formulation.

The present invention is further directed towards a method of preparinga liposomal pharmaceutical formulation comprising the steps ofdissolving a liposome forming agent in a solvent in a suitablecontainer; evaporating the solvent to form a lipid film on the surfaceof the container; adding a quantity of PVP iodine solution to saidcontainer with the lipid film therein to form a mixture; agitating saidmixture to produce liposomes; separating the liposomes and dispersingthe liposomes in a sodium chloride buffer solution; and freeze-dryingthe resultant dispersion. Additionally, the method described may includethe further step of filtering the dispersion through a high pressurefiltering means subsequent to liposome formation.

The invention also relates to a method of treating external woundscomprising the steps of applying a pharmaceutical preparation to anexternal wound, wherein the pharmaceutical preparation comprises anantiseptic agent, a wound-healing agent, or a combination thereof,encapsulated in a plurality of liposomes, and a pharmaceuticallyacceptable vehicle.

Additionally, the invention relates to a method of treating eyeinfections comprising the steps of applying a dose of a pharmaceuticalpreparation to the eye of a mammal having an eye infection, wherein thepharmaceutical preparation comprises an antiseptic agent, awound-healing agent, or a combination thereof, encapsulated in aplurality of liposomes, and a pharmaceutically acceptable vehicle. In apreferred embodiment, the pharmaceutical preparation is in the form of apharmaceutical eyedrop formulation.

Further advantageous embodiments of the invention will become apparentfrom the following paragraphs.

DETAILED DESCRIPTION OF THE INVENTION

The liposome preparations according to this invention permit protractedrelease of the agent or agents, and provide an extended and topicalactivity at the desired locus of action by interaction with cellsurfaces.

Experiments and research carried out by the instant inventors appear toshow that, even more unexpectedly, the preparations according to thisinvention do not only contain the active agent (e.g. povidone iodine)encapsulated in liposomes; there is also some amount of active agent(e.g. antiseptic agent, wound-healing agent) which is not containedinside the liposomes.

The preparations according to the present invention often show a markedinitial effect which is observed in addition to the slower, protractedrelease of the active agent from the liposomes. Without wishing to bebound to any theoretical explanation, it is presently assumed that inaddition to active agent encapsulated inside the liposomes, some activeagent is present outside of the liposomes, and probably loosely bound tothe outer surfaces of the liposomes. This could be due to association ofactive agent molecules with the liposomal membrane, or it could be dueto active agent molecules forming a layer on the liposomal surface,which layer partly or even fully coats the liposome externally. The typeand amount of this initial agent effect can, for example, be influencedby varying the concentration of the active agent.

Liposome preparations according to this invention thus make it possibleto achieve effects which cannot be provided by customary preparationssuch as solutions, ointments etc.

The active agent used in the preparations of the present invention maybe selected rom well-known agents which are classified, e.g., asantiseptic agents, wound-healing agents, and the like. Preferredantiseptic agents comprise the well-known pharmaceutical substancesproviding fast effect, a broad range of activity, low systemic toxicityand good tissue compatibility. They can e.g. be selected from the groupcomprising metal compounds, phenolic compounds, detergents, iodine andiodine complexes. A specifically preferred antiseptic agent is povidoneiodine.

Preferred wound-healing agents comprise substances which have beendescribed in the literature for such application. Preferredwound-healing agents include substances known to promote epithelization.These include vitamins, specifically from the vitamin B group,allantoin, azulenes, and mixtures thereof, and other agents well knownin the art having similar properties.

In preferred embodiments, the liposome preparations containingantiseptic and/or wound-healing agents can comprise further agents suchas anaesthetic agents. Inventive preparations can also contain customaryfurther agents, including adjuvants and additives, conserving agents orconsistency forming agents such as viscosity adjusting additives,emulgators etc.

The amphophilic substances generally known in prior art to form liposomemembranes can be employed in the context of the invention as long asthey are pharmaceutically acceptable for the intended application.Presently, liposome forming systems comprising lecithin are preferred.Such systems can comprise hydrogenated soy bean lecithin besidescholesterol and disodium succinate-hexahydrate. It is presentlyspecifically preferred to use hydrogenated soy bean lecithin as the solemembrane forming agent.

The known prior art methods for forming liposome structures cangenerally be used in the context of the invention. Broadly, thesemethods comprise mechanical agitation of a suitable mixture containingthe membrane forming substance and water or an aqueous solution.Filtration through suitable membranes is preferred in forming asubstantially uniform liposome size.

The size of the liposomes can vary over generally from about 20 to about20,000 nm. Liposomes with diameters form about 50 to about 4,000 nm arepreferred and liposomes of approximately 1,000 nm diameter are presentlymost preferred.

One presently preferred field of application is in ophthalmology, e.g.,in the treatment of bacterial and viral keratocon-junctivitis, and thepre-operative antiseptic prophylaxis.

A presently highly preferred use of the inventive liposome preparationsis in the local treatment of infections of the frontal part of the eye,especially when the liposome preparations contain povidone iodine. Alsoin this indication, the inventive antiseptic preparations, especiallythose containing PVP iodine, have the great advantage of not causingresistances and lead to much less allergic reactions, while permitting avery cost-efficient therapy with a broad spectrum of effect. A povidoneiodine liposome preparation according to this invention is e.g.effective against adenovirus, the most frequent cause of viralconjunctivitis. This effect is not provided by antibiotic agents.

A pharmaceutical preparation incorporating the liposomes of the presentinvention can provide extended release of an agent (e.g., an antisepticagent; wound-healing agent) in an environment of use over an extendedperiod of time. Such a time period may be, for example, of several hoursduration. More preferably, the time period is in the range of about 4 toabout 30 hours duration, and most preferably, from about 12 to about 24hours duration.

Further, a liposome preparation of antiseptic agent or a microbicidalagent such as povidone iodine provides protracted release of the agent,e.g., from liposomes located in the frontal part of the eye. This leadsto extended effect of the antimicrobial substance, and thus lessfrequent application, as compared with the customary antiseptic eyedroppreparations.

Preparations according to this invention forms, including solutions,dispersions, lotions, ointments and gels.

Generally, the amount of active agents in an inventive preparation willbe determined by the desired effect on the one hand and the carryingcapacity of the liposome preparation for the agent on the other hand.

Broadly, a solution or dispersion of active agent in an inventiveliposome preparation can range between the lower limit of effectivenessof the agent and the solubility or dispersability limit of the agent inthe respective solvent or dispersant.

Similar considerations broadly limit the amount of agent in liquids,lotions, creams, ointments or gels, or other such preparations capableof furthering the usefulness of the invention.

More specifically, for an antiseptic such as povidone iodine, a solutionor dispersion in an inventive liposome preparation can contain fromabout 0.1 to about 10 g of agent in approximately 100 g of preparation.Such a preparation will then typically contain from about 1 to about 5 gof liposome membrane forming substance especially lecithin per 100 g ofpreparation.

In a lotion, which can be a hydrophilic, amphophilic or a lipophiliclotion, a typical range of active agent will be from about 0.5 to about10 g agent, and from about 3 to about 8 g, preferably about 5 g ofliposome membrane forming agent such as hydrogenated soy bean lecithin,per 100 g of lotion. In the case of a hydrophilic lotion, electrolytesolution will often be used in preparing the liposome containing lotion.A lipophilic lotion will often be made from the agent, a membraneforming substance and lipophilic formation agents such as medium chainlength triglycerides etc.

Hydrophilic, lipophilic, or amphophilic creams are capable ofpreparation in accordance with the invention. A hydrophilic creamcomprising an inventive liposome preparation will generally comprisebetween 0.1 and 10 g agent, such as povidone iodine, together withbetween about 1 and 10 g membrane forming substance and further typicaloil in water (O/W) cream forming additives, per 100 g of cream.

A comparable amphophilic cream according to the invention will havesimilar contents of agent and membrane forming substance such aslecithin, and will have the typical further additives of an amphophiliccream.

A hydrophilic ointment according to the invention can broadly comprisefrom about 0.1 to about 10 g of active agent and from about 1 to about10 g liposome membrane forming substance such as lecithin, together withtypical prior art ointment basis substances such as Macrogol (TM) andwater, in 100 g of ointment.

A non-alcoholic hydrogel according to the invention could broadlycomprise from about 1 to about 5 g agent such as povidone iodine,approximately 2 g lecithin and gel forming substances such as Carbopol(TM), with pH-adjusting agent and water to form 100 g of hydrogel.

More specific formulations are notable from the embodiment example.

One preferred method for producing the liposomes of the presentinvention can generally be described as follows:

The lipid membrane forming components, e.g. lecithin, are dissolved in asuitable solvent such as chloroform or a 2:1 mixture of methanol andchloroform and are filtered under sterile conditions. Then, a lipid filmis produced on a sterile high surface substrate, such as glass beads, bycontrolled evaporation of the solvent. In some cases, it can be quitesufficient to form the film on the inner surface of the vessel used inevaporating the solvent, without using a specific substrate to increasethe surface.

An aqueous system is prepared from electrolyte components and the one ormore active agents to be incorporated in the liposome preparation. Suchan aqueous system can, for example, comprise 10 mmol/l sodium hydrogenphosphate and 0.9% sodium chloride, at pH 7.4; the aqueous system willfurther comprise at least the desired amount of the active agent, whichin the embodiment examples is povidone iodide. Often, the aqueous systemwill comprise an excess amount of agent or agents.

The liposomes are generally formed by agitating said aqueous system inthe presence of said film formed by the lipid components. At this stage,further additives can be added to improve liposome formation; forexample, sodium cholate can be added. Liposome formation can also beinfluenced by mechanical action such as pressure filtration through, forexample, polycarbonate membranes, or centrifuging. Generally, the rawliposome dispersion will be washed, for example, with electrolytesolution as used in preparing the above-described solution of the activeagent.

When liposomes with the required size distribution have been obtainedand washed, they can be redispersed in an electrolyte solution asalready described, often also comprising sugars such as saccharose or asuitable sugar substitute. The dispersion can be freeze-dried, and itcan be lyophilized. It can, prior to use, be reconstituted by additionof water and suitable mechanical agitation at the transition temperatureof the lipid component, which for hydrogenated soy bean lecithin is e.g.about 55° C.

In the following Examples, hydrogenated soy bean lecithin (EPISURON (TM)200 SH obtainable from Lukas Meyer, Germany or PHOSPOLIPON (TM) 90 Hobtainable from Nattermann Phospholipid GmbH, Germany) was used.However, other pharmaceutically acceptable liposome membrane formingsubstances can be used instead, and the person skilled in the art willfind it easy to select suitable alternative liposome forming systemsfrom what is described in prior art.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

The features and advantages of this invention will become notable inmore detail from the ensuing description of preferred embodiments. Inthese embodiments, which include a best mode, povidone iodine isexemplified as an antiseptic agent. This should not, however, beconstrued as a restriction of this invention to antiseptic agents or,among antiseptic agents, to povidone iodine, although such preparationsare specifically preferred.

EXAMPLE 1

In a 1000 ml glass flask, provided with glass beads for increasedsurface, 51.9 mg cholesterol and 213 mg hydrogenated soy bean lecithinwere dissolved in a sufficient amount of a mixture of methanol andchloroform in a 2:1 ratio. The solvent was then evaporated under avacuum until a film was formed on the inner surface of the flask and onthe glass beads.

2.4 g PVP iodine (containing about 10% available iodine) were separatelydissolved in 12 ml water.

Again in a separate vessel, 8.77 g sodium chloride and 1.78 gNa2HPOH·2H20 were dissolved in 400 ml water. Further water was added upto a total volume of 980 ml, and then, approximately 12 ml 1Nhydrochloric acid were added to adjust pH to 7.4. This solution was thentopped up with water to produce exactly 1000 ml.

In a fourth vessel, 900 mg saccharose and 57 mg disodium succinate weredissolved in 12 ml water.

The PVP iodine solution was then added to the lipid film in the flaskand the mixture was shaken until the film dissolved. This producedliposome formation from the hydrated lipids in the flask. The productwas centrifuged and the supernatant liquid was discarded. The asufficient quantity of saccharose solution was added to produce 12 ml ofsolution and the product was again centrifuged. Afterwards thesupernatant liquid was again discarded. At this stage, a further washingstep, using the sodium chloride buffer solution could be used.

After the last centrifugation step and discarding of the supernatant, asufficient quantity of sodium chloride buffer solution was added toproduce 12 ml of solution, and the liposomes were homogeneouslydistributed therein. The product was then distributed into vials eachcontaining 2 ml liposome dispersion, and the vials were then subjectedto a freeze-drying step.

After the freeze-drying each vial comprised about 40 mg solids.

The method of Embodiment Example I has a minor disadvantage in that thePVP iodine solution used, due to the high percentage of solids, israther viscous and thus more difficult to handle.

EXAMPLE II

In a 2000 ml flask provided with glass beads to increase surface, 173 mghydrogenated soy bean lecithin and 90 mg disodium succinate weredissolved in approximately 60 ml of a methanol/chloroform mix in a 2:1ratio. The solvent was removed under vacuum until a film was formed.

4 g PVP iodine (10% available iodine) were dissolved in 40 ml of thesodium chloride buffer solution described in Embodiment Example I, andwere added to the lipid film in the flask. The flask was then shakenuntil the film dissolved and liposomes were formed.

The product was centrifuged and the supernatant liquid was discarded.

To the thus produced liposome pellet, further sodium chloride buffersolution was added to produce 40 ml of solution, and the centrifugingstep was repeated. The supernatant was again discarded. At this stage,this washing step could be repeated where necessary.

After the final centrifuging and decanting step, sodium chloride buffersolution was again added to the precipitated liposomes to produce 40 mlof homogeneous dispersion. The homogenous dispersion was thendistributed into vials, each vial containing about 2 ml liposomedispersion, and the vials were then subjected to a freeze-drying step.This produced approximately 200 mg freeze-dried solids per vial.

From the freeze-dried solids of Examples I and II, further preparationswere made as described in subsequent embodiment Examples and TestReports.

Like that of Embodiment Example I, the above-described method uses ahydrating step after film formation in the presence of organic solventsand aims at inclusion rates of from about 5 to about 15%. These methodsgenerally produce rather large and often multilamellar liposomes.

The above-described- methods can be modified by a high pressurefiltering step through a suitable membrane such as a polycarbonatemembrane after the raw liposomes have been formed or after any of thesubsequent washing steps or directly by using high pressurehomogenization. This produces much smaller, unilamellar liposomes atincreased amounts of encapsulated agent.

Instead of high pressure homogenization, other prior art methods knownto provide small uniform sized liposomes can be employed.

EXAMPLE III

A hydrophilic (O/W) cream was prepared from 10 g hydrogenated soy beanlecithin/PVP iodine liposomes as described in Embodiment Example II;these were mixed with 4 g Polysorbate 40 (TM), 8 g cetylstearyl alcohol,8 g glycerol, 24 g white vaseline, and water to produce 100 g ofhydrophilic cream.

EXAMPLE IV

An amphophilic cream was prepared from 10 g hydrogenated soy beanlecithin/povidone iodine liposomes as described in Embodiment ExampleII; 7.5 g medium chain length triglyceride, 7 g polyoxyethyleneglycerolmonostearate, 6 g cetylstearyl alcohol, 8 g propylene glycol, 25 g whitevaseline, and water ad 100 g.

EXAMPLE V

A hydrophilic ointment which can be rinsed off with water was preparedusing 10 g of liposomal PVP iodine as described in Embodiment ExampleII, 55 g Macrogol 400 (TM), 25 g Macrogol 4000 (TM), and water ad 100 g.

EXAMPLE VI

A hydrogel was prepared from 4 g liposomal PVP iodine as described inEmbodiment Example II, 0.5 g Carbopol 980 NF (TM), sodium hydroxide adpH 7, water ad 100 g.

Further modifications of the above-described embodiments are envisaged.

Thus, the creams of Embodiment Examples III and IV can have anadditional content of an agent known to promote the healing of wounds,such as allantoin. Such an agent will be added in a pharmaceuticallyuseful concentration, in the case of allantoin in the range of 0.1 to0.5 g, per 100 g of cream. The wound healing agent can be incorporatedin the cream base, in which case it will largely be outside theliposomes. It can, however, be partly or mostly incorporated in theliposomes,in which case it will be added at a corresponding suitablestage of the liposome preparation method.

Similar alternatives are easily envisaged on the basis of the furtherEmbodiment Examples.

It is also possible to prepare embodiments similar to theabove-described ones, which comprise an agent capable of promoting thehealing of wounds instead of, and not in addition to, the antisepticagent as e.g. povidone iodine disclosed in the above EmbodimentExamples. Presently, it is however preferred to use a wound healingpromoting agent (if at all) in addition to an antiseptic agent.

For application of the inventive preparations to a patient, knownsystems can be used, such as pneumatic pump applicators, two-chamber gaspressure packs etc.

In a pneumatic pump applicator, a bellows, device is provided between anupstream and a downstream valve, both valves operating one way in thesame direction. A supply of pharmaceutical preparation, such as anointment or gel, is contained in a reservoir up-stream of thevalves-and-bellows device.

When compressing the bellows, the downstream valve opens and permits adosed amount of preparation to leave the device for application. Whenthe bellows is extended, this valve shuts and prevents reentry of thepreparation. At the same time, the upstream valve opens and permitspreparation from the reservoir to enter into the bellows, for releasethrough the downstream valve upon the next compression step of thebellows.

The reservoir is sealed by a closure element which can move through thereservoir like a piston moves in a cylinder. By the stepwise emptying ofthe reservoir, this closure element is sucked into the reservoir, sothat the remaining amount of pharmaceutical preparation in the reservoiris always sealed off, while at the same time the reservoir can beemptied.

Such a device is useful for pasty preparations, creams, ointments etc.

In a two-chamber gas pressure pack, the pharmaceutical preparation iscontained in a bag of flexible plastics film material. Often, this ishigh pressure polyethylene.

The bag is contained inside a gas tight pressure vessel which furthercontains a supply of pressurizing gas, very often a compressed inert gaslike nitrogen.

The plastic film bag has only one outlet, which is gas-tightly connectedto the interior wall of the pressure vessel, surrounding a singleopening thereof. The pressurized gas in the vessel tends to compress thebag, driving the pharmaceutical preparation inside the bag out throughthe opening of the bag and thus through the opening of the vessel. Avalve and in case, spray-held device is provided in the vessel mouth.Operating the valve releases a spray mist, a jet of liquid or a portionof flowable solid such as cream. Using such a system, solutions,emulsions, creams, ointments and gels, dosed and applied.

Dosing inventive preparations efficiency and acceptability tests werethen carried out, as follows:

Test I

This was an in-vitro-test of the bactericidal effect provided by aninventive povidone iodine liposome preparation. The test was based onthe quantitative suspension test as described in “Richt-linien derDeutschen Gesellschaft fur hygiene und Mikrobiologie”, 1989. In thistest, the bactericidal agent is used to kill staphylococcus aureus (ATCC29213), a major problem in hospital hygiene.

The liposome preparation used was that of Embodiment Example I. Atdifferent contact times between 1 and 120 minutes, the minimumconcentration of the preparation in water was determined which wascapable of killing the staphylococci.

The results are shown in Table 1.

TABLE I Contact Time (Minutes) Bactericidal Concentration 1, 2, 3, 4≧0.060% 5, 30, 60 120 ≧0.015% 120 ≧0.007%

The results show that at short contact times (between 1 and 4 minutes)the bactericidal concentration is as low as 0.06% and that at longcontact times (120 minutes) the bactericidal concentration can be as lowas 0.007%.

Test II

The second test was a placebo-controlled clinical study of the localacceptability (at the eye) of an inventive povidone iodine liposomepreparation. An eyedrop formulation was made using the liposomes ofEmbodiment Example II. It was tried on 15 male test persons. Theinventive preparation was always used on one eye of the test person,with physiological sodium chloride solution added as a comparison to therespective other eye.

Specifically, each test person received one drop of PVP iodine liposomepreparation in the right eye and one drop of physiological sodiumchloride solution in the left eye, and this was twice repeated at hourlyintervals. After 5, 30, 65, 95, 125 and 150 minutes as well as after 24hours after the first application, symptoms were determined. Thesesymptoms included hyperaemia, as measured with a slit/lamp microscope;burning; itching, and tear flow. Each symptom was measured according toa 4 point score with 0 corresponding to no symptom, 1 corresponding to alow degree, 2 corresponding to a medium degree and 3 corresponding to astrong degree of symptom appearance.

A sum score was calculated from the degree scores of all four symptomsand the 7 determination time points. The sum score could thus varybetween 0 (=0 times 0 times 0) and 84 (=4 times 3 times 7).

The test persons were between 21 and 36 years old, with an average of 30years of age. All test persons were healthy and not under medicationduring the test. Specifically, any illnesses of the eye and of thethyroid were excluded.

One test person was not evaluated for sum score since one control ofsymptoms after 150 minutes was missed.

The results are notable from Table II.

Overall, the sum score on both eyes was extremely low. It is surprisingthat on average, the sum score for the eyes treated with the povidoneiodine liposome preparation was even lower than that for the eyesreceiving physiological sodium chloride solution.

TABLE II PVP-I-Liposomes Phys. NaCl-Solution Sum score Number of testpersons 0 11 6 1 3 6 2 0 2 3-84 0 0 Average 0.21 0.71 Standard Deviation0.43 0.73 Median 0 1 p-Value 0.02

Eleven test persons treated with the invention's povidone iodineliposome preparation showed no symptoms whatsoever. Three test personshad slight hyperaemia, one felt some very slight burning (this is theabove-mentioned test person who could not be evaluated for sum score).On the contrary, only six test persons exhibited no symptoms afterreceiving physiological sodium chloride solution. Four test personsexperienced burning, one of them at two subsequent time points. One testperson experienced slight burning and itching of the left eye. A totalof four test persons showed some hyperaemia.

The examples provided are not meant to be exclusive. Many othervariations of the present invention will be obvious to those skilled inthe art, and are contemplated to be within the scope of the appendedclaims.

1. A pharmaceutical preparation for external application comprising anantiseptic agent, a wound-healing agent, or a combination thereof,encapsulated in a plurality of liposomes.
 2. A pharmaceuticalpreparation according to claim 1, further comprising a pharmaceuticallyacceptable vehicle, wherein a portion of said antiseptic agent or saidwound-healing agent, or said combination thereof contained in thepreparation is not encapsulated in said liposomes.
 3. A pharmaceuticalpreparation according to claim 2, wherein at least the greatest part ofsaid antiseptic agent or said wound healing promoting agent, or saidcombination thereof, is encapsulated inside the liposomes.
 4. Apharmaceutical preparation according to claim 1 wherein said antisepticagent is selected from the group consisting of metal compounds such asmercury compounds, phenol derivatives such as thymol, eugenol andhexachlorophene detergents, iodine and iodine complexes.
 5. Apharmaceutical preparation according to claim 4 wherein said antisepticagent is povidone iodine.
 6. A pharmaceutical preparation according toclaim 1 wherein said wound-healing agent is selected from the groupconsisting of allantoin, an azulene compound, a compound from thevitamin B series, and combinations of the foregoing.
 7. A pharmaceuticalpreparation according to claim 1 wherein the preparation contains atleast one antiseptic and at least one wound healing promoting agent. 8.A pharmaceutical preparation according to claim 1 wherein said liposomesare of a substantially uniform size in the range from about 20 to about20,000 nm.
 9. A pharmaceutical preparation according to claim 8 whereinsaid liposomes are of a substantially uniform size in the range fromabout 50 to about 4,000 nm.
 10. A pharmaceutical preparation accordingto claim 8 wherein said liposomes are of a substantially uniform size inthe range form about 500 to about 2,500 nm.
 11. A pharmaceuticalpreparation according to claim 8 wherein said liposomes are of asubstantially uniform size of about 1,000 nm diameter.
 12. Apharmaceutical preparation according to claim 2 wherein the preparationreleases said antiseptic agent, said wound-healing agent, or combinationthereof, in an environment of use over an extended time period.
 13. Apharmaceutical preparation according to claim 12 wherein said extendedtime period comprises several hours duration.
 14. A pharmaceuticalpreparation according to claim 12 wherein the preparation releases saidantiseptic agent, said wound-healing agent, or combination thereof, atapproximately the same release rate over the release time period.
 15. Apharmaceutical preparation according to claim 2 further comprising atleast one anesthetically active agent.
 16. A pharmaceutical preparationaccording to claim 2 further. comprising conserving agents andconsistency forming additives.
 17. A pharmaceutical preparationaccording to claim 2, wherein said vehicle is a liquid and saidpreparation is in the form of a solution or dispersion comprisingliposomes.

wherein said preparation is in the form of a pharmaceutical droppreparation.
 19. A pharmaceutical preparation according to claim 2,wherein said vehicle comprises a hydrophilic, lipophilic, or amphophiliccream base and said preparation is in the form of a cream.
 20. Apharmaceutical preparation according to claim 2, in the form of apharmaceutical oil in water or a water in oil lotion.
 21. Apharmaceutical preparation according to claim 2, wherein said vehicle isan ointment base and the preparation is in the form of a pharmaceuticalointment.
 22. A pharmaceutical preparation according to claim 2, whereinsaid vehicle is a gel base and the preparation is in the form of apharmaceutical gel.
 23. A pharmaceutical preparation according to claim22, wherein said vehicle is a nonalcoholic hydrogel base.
 24. A.pharmaceutical preparation according to claim 2, wherein thepharmaceutical preparation is in the form of a pharmaceutical eyedropformulation; wherein said liposomes comprise a pharmaceuticallyacceptable liposome membrane forming substance; wherein said antisepticagent comprises a 0.1 to 2% PVP iodine solution at least most of whichis encapsulated within said liposomes; and wherein said liposomes are ofsubstantially uniform size between about 50 and about 4,000 nm, and saidformulation may additionally comprise customary additives, adjuvants andauxiliary substances of a pharmaceutical eyedrop formulation.
 25. Apharmaceutical preparation according to claim 24 wherein said liposomesare of substantially uniform size, with diameters of about 1,000 nm. 26.A method of preparing, a liposomal pharmaceutical formulation comprisingthe steps of: dissolving a liposome forming agent in a solvent in asuitable container; evaporating said solvent to form a lipid film on theinner surface of said container; adding a quantity of PVP iodinesolution with said lipid film therein to form a mixture; agitating saidmixture to produce liposomes; separating said liposomes; dispersing saidliposomes in a sodium chloride buffer solution; and freeze-drying saiddispersion.
 27. A method of preparing a liposomal pharmaceuticalformulation according to claim 26, further comprising the step offiltering said dispersion or said mixture through a high pressurefiltering means subsequent to liposome formation.
 28. A method oftreating external wounds comprising the steps of: applying anantiseptically active amount of a pharmaceutical preparation to anexternal wound, wherein said pharmaceutical preparation comprises anantiseptic agent, a wound-healing agent, or a combination thereof,encapsulated in .a plurality of liposomes dispersed in apharmaceutically acceptable vehicle.
 29. A method of treating eyeinfections comprising the steps of: applying an antiseptically effectivedose of a pharmaceutical preparation to the eye of a mammal having aneye infection, wherein said pharmaceutical preparation comprises anantiseptic agent, a wound-healing agent, or a combination thereof,encapsulated in a plurality of liposomes and dispersed in apharmaceutically acceptable vehicle.
 30. A method of treating eyeinfections as recited in claim 29, wherein said pharmaceuticalpreparation is in the form of a pharmaceutical eyedrop formulation;wherein said liposomes comprise a pharmaceutically acceptable liposomemembrane forming substance; wherein said antiseptic agent comprises a0.1 to 2% PVP iodine solution at least most of which is encapsulatedwithin said liposomes; and wherein said liposomes are of substantiallyuniform size between about 50 and about 4,000 nm, and said formulationmay additionally comprise customary additives, adjuvants and auxiliarysubstances of a pharmaceutical eyedrop formulation.